In the publication by Gärtner, “Tagunsbeitrag: Analyse von neuen Plastifizierungskonzepten für das Mikrospritzgiessen”. 21. INTERNATIONALES KUNSTOFFTECHNISCHES KOLLOQUIUM, 27.02-Jan. 3, 2002, 28 Feb. 2002 Feb. 28, 2002), pages 1-19, the use of an ultrasound device for moulding plastic micro-pieces is described.
Other patents related to this technology are U.S. Pat. No. 4,115,489, EP 930144, JP 6328451 and U.S. Pat. No. 4,784,591.
WO 2009/027569, belonging to present applicant, describes an ultrasound device for moulding plastic micro-pieces that uses ultrasonic vibration as a source of energy for the melting the plastic, contemporarily with the access to the moulding cavity or cavities by, or the filling thereof with the molten plastic. This patent application describes the use of a sonotrode, which works as a plasticising unit operating through ultrasonic vibration, and an assembly arrangement of said sonotrode in an annular support provided with an extended portion that is inserted inside and attached to a member having outer spherical surfaces that makes up a ball joint allowing a swivelling movement for the sonotrode assembly and providing the self-centring of the tip thereof inside the melting chamber.
The apparatus of the present invention is characterised by an alternative assembly arrangement of a sonotrode.